Surface dressing machine



Aug. 1l, 1931. J. l.. scHwABE, JR 1,818,361

SURFACE DRESSING MACHINE Filed May 3l, 1928 vOG() C) @GO O G G 0 Q a@ 4/4/ /4/ f5 /z Y lll/,11111111 l N VEN TOR. Z22/5F51?. 55m/M455 17j?.

BY E

ATTORNEY.

hama Aug. 11, 1931 PATENT? OFFICE Joslin: L. scnwann, ne., or unwauxmi. wisconsin SURFACE DRESSING MACHINE Application illed Hay 31, 1928. Serial No. 281,751.

This invention relates to portable, power driven, surface dressin machines of the type involving a pair o oppositely reciprocating dressin elements.

Earlier mac ines of this type have been found objectionable because of the inability to prevent the escape and deposit of lubricant from the machine to the dressing elements and to the work being treated.

These elements are invariably arranged beneath the frame of the machine and constitute a support therefor, andas heretofore designed, it has been common practice to mount them in exposed guides on the base of the frame. When so mounted ample lubrication of the guides invariably results in the escape of lubricant to the work.

One object of the present invention is the rovision of a machine of the type mentloned in which the parts are so constructed and yarranged as to eliminate the above objection.

Another object is the provision in a machine of the type mentioned of improved means for mounting the pair of dressing elements for reciprocation parallel to each other and in opposite directions.

Another object is the provision of an improvedself-contained electric machine of the type mentioned of light weight, and of simple and economical design.

Another object is the provision in a machine of the type mentioned of an improved and elicient driving connection between the electric motor and the dressing elements.`

Other objects and advantages Will appear from the following description of an illustrative embodiment of the present invention.

In the drawings Figure 1 is a side elevation, partly in section, of a surface dressing machine constructed in accordance with the present invention.

Fig. 2 is a horizontal sectional view taken substantially along the line 2 2 of Figure 1.

The machine selected for illustration is intended primarily for sanding although it may be readily converted into a brushing, scraping, scouring or polishing machine without material change. The main frame of the machine shown is in the form of a substantially rectangular casing 10 closed at the bottom by a removable base plate 11 and at the top by a removable cover plate 12. The plate 12 supports and forms a part of a housing 13 of an electric motor of a well-known type. The motor armature shaft 14 is lvertically arranged and pro'ects through the plate 12 into the interior o the casing 10.

The casing of the machine is supported upon a pair of elongated shoes 15 arranged side by side beneath the casing and mounted for simultaneous lengthwise reciprocation in opposite directions. The shoes are substantial du licates of each other. Each of the shoes shown comprises an elongated rectangular-plate 16 of metal having a similarly shaped wooden block 17, applied to the under face thereof, the block being designed to receive and retain a sheet 18 of abrasive material such as sand paper or the like. In this instance the end portions 19 of each block are hingedly connected to the intermediate or main portion thereof through strips 20 of spring steel, which yieldably retain the end portions 19 against the plate but permit the same to be swung downwardly, as indicated in dotted lines in figure 1. Each plate 16 is provided, adjacent each end with a plurality of depending teeth or prongs 21, adapted to pierce the sheet of abrasive material and thus coact with the end portions 19 of the block to retain the material thereon.

To apply the material to the block one end portion 19 of the block is swung downwardly from the plate 1G and one end of the material applied thereover, after which that end portion of the block is returned to its normal position against the plate so as to force the prongs 21 through the. material and grip the material between the plate and end portion. Then the other end portion 19 is swung downwardly, the other end of the material stretched thereover, and that end portion similarly returned to its normal position againstthe plate 16, so as to force the prongs 21 through the material. The material is thus securely retained at both ends and rendered taut by the hinge action of the end portions of the block.

A pair of upright brackets 22, rigidly fixed to the plate 16 of each shoe 15 -adjacent the ends thereof, provide a rigid driving connection and support between each shoe and a bar 23, mounted for lengthwise reciprocation through the ends of the casing 10. The brackets 22 are releasably 4fixed to the opposite ends of the bars 23 by appropriate means such as clamp screws 24, Each bar shown comprises an intermediate rectangular portion 25 and circular end portions 26, the latter being closely fitted for reciprocation within flanged bushings 27, removably fixed in suitable openings 28, formed in the end walls of the casing. The openings 28 are preferably of such size as to permit withdrawal of the bar 23 therethrough upon removal of the associated bushing. The bushings 27 shown are provided with appropriate leak proof packing glands 29.

The intermediate rectangular portion 25 of each bar 23 is guided by and between a horizontal rail 30 lixed to a side wall of the casing 10, and an adjustable block 31 mounted upon the base plate 11 of the casing intermediate the bars, appropriate ball bearings 32 being interposed between the bars, rails, and block to reduce friction to a minimum. In this instance the balls of each bearing ride in V-grooves formed in the opposite edges of the bars, rails, and block and appropriate ball retainer cages 33 are provided whose lengthwise travel are limited by suitable means such as pin and slot connections 34.

The guide block 3l comprises a main body portion 35 and a tapered gib 36 having a tongue and groove connection 37 therewith. The gib 36 is lengthwise adjustable relative to the body portion V35 under the control of a screw 38, threaded in the body portion and having a head 39 which bears against the end of the gib. The screw 38 is accessible through a hole in the casing which is normally closed by a plug 38. The body portion 35 is adjustably xed to the base plate 11 by appropriate meanssuch as a pair of screws 40 which extend upwardly through transversely enlarged holes 41 in the plate and into threaded holes in the body' portion. The ide block may thus be expanded by len wise adjustment of the gib 36, under the action of the screw 38, to thereby take up any slack that may exist between the bars 23, rails 30, and guide block. This adjustment is effected while the screws 40 are in a loose condition so that the guide block is thus laterally free to automatically center itself between the bars, after which these screws are tightened to thereby securely anchor the block. v

The two bars 23, and consequently the shoes 15, are simultaneously reciprocated in opposite directions by power transmitted from the shaft 14 of the motor through an appropriate speed reduction ear set preferably such as will now be described. In the machine shown the gear set is supported by an integral partition or web 42 horizontally disposed within the casing 1 0. The gear set includes a pinion 43 having a hollow hub 44, for receiving the end of the shaft 14, and to which it is operatively connected through a pin and slot connection 45. Pinion 43 meshes with a lar e gear 46, fixed to the upper end of a sha t 47, journaled in the partition 42, and carrying a pinion 48 at its lower end. Pinion 48 meshes with a large gear 49 fixed to the lower end of a stub shaft (not shown) journaled in the web, and large gear 49 meshes with a second gear 50 of the same size fixed to the lower end of a similar shaft 51 journaled in the web. This gear train provides a double speed reduction between the motor and the gears 49 and 50. Gear 50 is disposed adjacent one corner of the casing 10 and carries a crank pin 52, which is connected to a stud 53 in one of the bars 23 through a suitable pitman 54; and gear 49 is disposed adjacent the diagonallyopposite corner of the casing and carries a similar crank pin 55, which is connected to a stud 56 in the other bar 23. It will be noted that these gears rotate at the same rate and in opposite directions and that the crank ins 52 and thereof are so set as to e ect the simultaneous reciprocation of the bars 23 1n opposite directlons.

It will also be noted that by the arrangement of parts hereinabove described all surfaces exposed to wear are disposed wholly within the casing where they .may receive ample lubrication without danger of the lubricant escaping to the abrasive elements or to the work. In fact the casing is practically leak-proof and the enclosed parts may be who ly immersed in a body of lubricant therein.

The machine may be equipped with a forward handle 57, which is shown carried by a bracket plate 58, attached to the top plate 12 of the casing, and with a rear handle 59 attached to the motor housing 13, which in this instance provides a conduit for the power lead 60 for the motor. The' motor 41s controlled by an appropriate switch 61 carried by the handle 59. The machine shown is also equipped with appropriate guards 62., removably applied to the ends of the casmg, which serve to partially house le projecting ends of the reciprocating bars Various changes may be made in the embodlment of the invention hereinabove specically described without departing from the projecting en s of said bars.

or sacrificing the advantages of the invention as defined in the appended claims.

I claim 1. A portable surface dressing machine comprislng a lubricant retainer casing, a plurality of bars mounted for lengthwise reciprocation through opposite walls of said casing, means enclosed 1n said casing for reciprocating said bars simultaneously in oplposite directions, and a lurality of shoes be ow said casin carrie and 2. A portable surface dressing machine comprising a lubricant retainer casing, a plurality of bars mounted for lengthwise reciprocation through opposite walls of said casing, guide means for said bars enclosed Within said casing, means within said casing for reciprocating said bars simultaneously in opposite directions, and a plurality of shoes below said casing carried and guided by the projecting ends of said bars.

3. A portable surface dressing machine comprising a lubricant retainer casing, a plurality of parallel bars mounted for lengthwise reciprocation through opposite walls of said casing, an electric motor carried by said casing, means within said casing for reciprocating said bars simultaneously in opposite directions, speed reduction gearing between said motor and means for riving said means, and a pluralit of shoes below said casing carried and gui ed by the projecting ends of said bars.

4. A portable surface dressing machine comprising a lubricant retainer casing, a

pair of parallel bars mounted for lengthwise v reciprocation through opposite walls of said casing, a gear adjacent one corner of said casing for reci rocating one of said bars, a second gear a jacent the diagonally opposite corner of said casing for driving the other of said bars, gearing for driving said gears, an electric motor carried b said casing for driving said gearing, an a pair of shoes below said casing carried and guided by the projecting ends of said bars.

5. A portable surface dressing machine comprismg a casing, an electric motor, a motor support closing the top of said casing, a s ed reduction gear set Within said casin riven by said motor, a pair of parallel ars projecting through opposite walls of said casing, driving connectlpns between said gear set and bars for reciprocating said bars lengthwise in opposite directions, a closure for the bottom of said casing, and a pair of shoes spaced from and below said closure and driven by said bars. j

6. A portable surface dressing machine comprising a casing, a motor support closing the top of said casing, a motor armature shaft projecting downwardly into said casing, a pinion within said casing, an axially separable driving connection between guided by p said shaft and pinion, a gear meshingk with said pinion, a second pinion driven by said gear, a second gear meshing with said second pinion, a third gear meshing with said second gear, and a pair of reciprocating shoes below said casing driven respectively by said second and third gears.

7. A portable surface dressing machine comprising a casing, a pair of parallel bars projecting through opposite walls of said casing, means within said casing for guiding said bars, anti-friction bearings between said bars and guiding means, means in said casing for reciprocating said bars len hwise in opposite directions, anda pair o shoes carried by the' projecting ends of said bars and disposed below and spaced from said casing.

8. A portable surface dressing machine comprising a casing, a pair of'parallel bars projecting throu h opposite walls of said casing, a pair of s oes below said casing carried by the projecting ends of said bars, and means within said casing for guiding said bars, said means including a laterally expansible guide block between said bars, and means for expanding said block.

In witness whereof, I hereunto subscribe my name this 28th day of May, 1928.

JOSEPH L. SCHWABE, JB. 

